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744SPX wrote:I saw the article as well. Not sure why they are saying 45k as a 10% increase over the F135 (43k) would be 47.3K.
Going from 43k to 45k is hardly worth mentioning. That's even less than the planned F135 upgrade.
As the F135 was shown years ago to be capable of a 50k rating, the XA100 should most certainly be capable of that considering its 15+ years newer.
50k would make a real difference for the C model and give the F-35A a 1:1 thrust to weight ratio with full internal fuel and full internal (6) AMRAAM loadout at takeoff.
JayinKitsap wrote:Is this a demonstration program?, I recall that there is only the Pratt engine for the F35 procurement.
Max Q wrote:I wonder if it will boost the F35’s rather anemic top speed,
tommy1808 wrote:Max Q wrote:I wonder if it will boost the F35’s rather anemic top speed,
I do believe the top speed is not thrust limited but by the diverterless inlet efficency dropping of a cliff.
Best regards
Thomas
LightningZ71 wrote:The F-35B requires a rather specific design and spec of PTO from the engine for the lift fan. These engines are significantly different in how they are designed where the PTO would be, and it likely has different power available there. I expect that the B will require its own engine upgrade program, though, arguably, it is the model that would most benefit from an improved engine. It has the most restricted fuel capacity of the three for starters.
744SPX wrote:LightningZ71 wrote:The F-35B requires a rather specific design and spec of PTO from the engine for the lift fan. These engines are significantly different in how they are designed where the PTO would be, and it likely has different power available there. I expect that the B will require its own engine upgrade program, though, arguably, it is the model that would most benefit from an improved engine. It has the most restricted fuel capacity of the three for starters.
It also has the draggiest, most non-area-ruled airframe of the three thanks to the lift fan housing behind the cockpit.
Max Q wrote:744SPX wrote:LightningZ71 wrote:The F-35B requires a rather specific design and spec of PTO from the engine for the lift fan. These engines are significantly different in how they are designed where the PTO would be, and it likely has different power available there. I expect that the B will require its own engine upgrade program, though, arguably, it is the model that would most benefit from an improved engine. It has the most restricted fuel capacity of the three for starters.
It also has the draggiest, most non-area-ruled airframe of the three thanks to the lift fan housing behind the cockpit.
Good point, all three versions appear very draggy to me, As wide as it is it looks like it should have two engines
I didn’t realize that lift fan housing added that much drag
texl1649 wrote:It’s basically a bunch of oversized integral fuel tanks built around a massive engine and some tiny wings, with a few bomb bays, but also with stealth incorporated from the front aspect. Kind of a modern F-104 on roids if you will.
Max Q wrote:744SPX wrote:I saw the article as well. Not sure why they are saying 45k as a 10% increase over the F135 (43k) would be 47.3K.
Going from 43k to 45k is hardly worth mentioning. That's even less than the planned F135 upgrade.
As the F135 was shown years ago to be capable of a 50k rating, the XA100 should most certainly be capable of that considering its 15+ years newer.
50k would make a real difference for the C model and give the F-35A a 1:1 thrust to weight ratio with full internal fuel and full internal (6) AMRAAM loadout at takeoff.
Not sure what the baseline was, what seems significant about this GE engine is that it’s exceeding promised thrust margins significantly along with substantial improvements in fuel burn
Agree that this should improve performance dramatically, I wonder how much actually, it should help transonic acceleration which appeared to be a weak point
I wonder if it will boost the F35’s rather anemic top speed, also if this ‘third stream’ may have an affect like a high bypass turbofan in quieting an incredibly noisy aircraft !
Max Q wrote:Good points, otoh the F105 would leave the F35 in the dust
wingman wrote:Max Q wrote:Good points, otoh the F105 would leave the F35 in the dust
You mean the F35 would fly through the dust of the F105 that didn't know what just blew it up. I think that's the only or primary point of the F35. If a squadron of them end up with just bullets trying to outshoot a squadron of newer Migs or Raffles it probably won't end well.
kitplane01 wrote:Max Q wrote:744SPX wrote:I saw the article as well. Not sure why they are saying 45k as a 10% increase over the F135 (43k) would be 47.3K.
Going from 43k to 45k is hardly worth mentioning. That's even less than the planned F135 upgrade.
As the F135 was shown years ago to be capable of a 50k rating, the XA100 should most certainly be capable of that considering its 15+ years newer.
50k would make a real difference for the C model and give the F-35A a 1:1 thrust to weight ratio with full internal fuel and full internal (6) AMRAAM loadout at takeoff.
Not sure what the baseline was, what seems significant about this GE engine is that it’s exceeding promised thrust margins significantly along with substantial improvements in fuel burn
Agree that this should improve performance dramatically, I wonder how much actually, it should help transonic acceleration which appeared to be a weak point
I wonder if it will boost the F35’s rather anemic top speed, also if this ‘third stream’ may have an affect like a high bypass turbofan in quieting an incredibly noisy aircraft !
I believe noise is a function of velocity of exhaust. Modern engines are quieter in large part because the larger bypass ratio reduces the exhaust velocity needed to produce a given thrust.
At max-thrust, the third stream will go through the core, gain maximum velocity, and probably be about as loud as the previous engine at max thrust. It might even be a bit louder because it's generating a higher thrust total. So on takeoff, I would not expect to see much quieting.
At lower thrusts the third stream would avoid the core, exist with a lower velocity, and reduce noise. So while cruising or landing it might be quieter.
It's actually a different engine, not just a modification of the existing engine, so lots of things will be different. It might have a different noise profile for that reason alone.
Max Q wrote:wingman wrote:Max Q wrote:Good points, otoh the F105 would leave the F35 in the dust
You mean the F35 would fly through the dust of the F105 that didn't know what just blew it up. I think that's the only or primary point of the F35. If a squadron of them end up with just bullets trying to outshoot a squadron of newer Migs or Raffles it probably won't end well.
Remains to be seen, it’s all theoretical at the moment
CRJockey wrote:Max Q wrote:wingman wrote:
You mean the F35 would fly through the dust of the F105 that didn't know what just blew it up. I think that's the only or primary point of the F35. If a squadron of them end up with just bullets trying to outshoot a squadron of newer Migs or Raffles it probably won't end well.
Remains to be seen, it’s all theoretical at the moment
What remains to be seen? The superiority of the F35 vs F105? Or the knife fight superiority of a Rafale or MiG?
Max Q wrote:kitplane01 wrote:Max Q wrote:
Not sure what the baseline was, what seems significant about this GE engine is that it’s exceeding promised thrust margins significantly along with substantial improvements in fuel burn
Agree that this should improve performance dramatically, I wonder how much actually, it should help transonic acceleration which appeared to be a weak point
I wonder if it will boost the F35’s rather anemic top speed, also if this ‘third stream’ may have an affect like a high bypass turbofan in quieting an incredibly noisy aircraft !
I believe noise is a function of velocity of exhaust. Modern engines are quieter in large part because the larger bypass ratio reduces the exhaust velocity needed to produce a given thrust.
At max-thrust, the third stream will go through the core, gain maximum velocity, and probably be about as loud as the previous engine at max thrust. It might even be a bit louder because it's generating a higher thrust total. So on takeoff, I would not expect to see much quieting.
At lower thrusts the third stream would avoid the core, exist with a lower velocity, and reduce noise. So while cruising or landing it might be quieter.
It's actually a different engine, not just a modification of the existing engine, so lots of things will be different. It might have a different noise profile for that reason alone.
Very insightful
This is such a revolutionary engine that promises such great improvements I wonder if some of this technology could eventually migrate over to civilian
jet transport engines
Max Q wrote:CRJockey wrote:Max Q wrote:
Remains to be seen, it’s all theoretical at the moment
What remains to be seen? The superiority of the F35 vs F105? Or the knife fight superiority of a Rafale or MiG?
What remains to be seen is whether the F35 can prevail in an airborne fight against a contemporary
CRJockey wrote:Max Q wrote:CRJockey wrote:
What remains to be seen? The superiority of the F35 vs F105? Or the knife fight superiority of a Rafale or MiG?
What remains to be seen is whether the F35 can prevail in an airborne fight against a contemporary
Awkwardly cautious position I think. But yeah, on technical terms we have yet to see an encounter.
VSMUT wrote:
Drag increases almost exponentially with speed. You can't overcome poor aerodynamics by just adding more power.
mxaxai wrote:VSMUT wrote:
Drag increases almost exponentially with speed. You can't overcome poor aerodynamics by just adding more power.
While drag may play a role, I'm quite sure that the F-35 top speed is limited by the materials and the temperatures they can tolerate. It has so much thrust available, I'd be very surprised if that was the reason to limit it to M1.6. For the B and C, the temperature problems are well documented https://www.defensenews.com/air/2019/06 ... h-coating/
A new engine that would enable supercruise might mitigate some of those issues at low supersonic speeds. Still, aerodynamic heating at high speeds would remain troublesome.
mxaxai wrote:VSMUT wrote:
Drag increases almost exponentially with speed. You can't overcome poor aerodynamics by just adding more power.
While drag may play a role, I'm quite sure that the F-35 top speed is limited by the materials and the temperatures they can tolerate. It has so much thrust available, I'd be very surprised if that was the reason to limit it to M1.6. For the B and C, the temperature problems are well documented https://www.defensenews.com/air/2019/06 ... h-coating/
A new engine that would enable supercruise might mitigate some of those issues at low supersonic speeds. Still, aerodynamic heating at high speeds would remain troublesome.
VSMUT wrote:mxaxai wrote:VSMUT wrote:
Drag increases almost exponentially with speed. You can't overcome poor aerodynamics by just adding more power.
While drag may play a role, I'm quite sure that the F-35 top speed is limited by the materials and the temperatures they can tolerate. It has so much thrust available, I'd be very surprised if that was the reason to limit it to M1.6. For the B and C, the temperature problems are well documented https://www.defensenews.com/air/2019/06 ... h-coating/
A new engine that would enable supercruise might mitigate some of those issues at low supersonic speeds. Still, aerodynamic heating at high speeds would remain troublesome.
The F-35 is a very draggy aircraft. A result of the big internal bomb bay, massive engine and a common airframe that is designed to accommodate the massive lift fan on the F-35B. And as Tommy brings up, the inlets. Drag increases almost exponentially with speed, and you need to overcome the drag. At some point you'd have to double the power to achieve a meaningful improvement. Adding power is not the solution to going faster once you reach a certain point, and everything I've read and seen about the F-35 seems to indicate that it is pretty close to that point.
ThePointblank wrote:VSMUT wrote:mxaxai wrote:While drag may play a role, I'm quite sure that the F-35 top speed is limited by the materials and the temperatures they can tolerate. It has so much thrust available, I'd be very surprised if that was the reason to limit it to M1.6. For the B and C, the temperature problems are well documented https://www.defensenews.com/air/2019/06 ... h-coating/
A new engine that would enable supercruise might mitigate some of those issues at low supersonic speeds. Still, aerodynamic heating at high speeds would remain troublesome.
The F-35 is a very draggy aircraft. A result of the big internal bomb bay, massive engine and a common airframe that is designed to accommodate the massive lift fan on the F-35B. And as Tommy brings up, the inlets. Drag increases almost exponentially with speed, and you need to overcome the drag. At some point you'd have to double the power to achieve a meaningful improvement. Adding power is not the solution to going faster once you reach a certain point, and everything I've read and seen about the F-35 seems to indicate that it is pretty close to that point.
Not really; the frontal aspect of a F-35C is about the same as a F/A-18E/F Super Hornet:
https://www.f-16.net/forum/viewtopic.ph ... 2&p=248729
Comparing a F-35A to a Eurofighter or Rafale:
Also, the Super Hornet, Rafale, and Eurofighter all carry their weapons externally; external weapons, fuel tanks and pylons significantly increase drag. Not many fighters out there can claim that they can carry a pair of 2,000lb bombs, enough fuel for a typical strike mission and 2 air to air missiles, and fly at their top rated speed for as long as they have enough fuel to keep going. Every other fighter is subsonic only with anything hanging off of them.
Max Q wrote:ThePointblank wrote:VSMUT wrote:
The F-35 is a very draggy aircraft. A result of the big internal bomb bay, massive engine and a common airframe that is designed to accommodate the massive lift fan on the F-35B. And as Tommy brings up, the inlets. Drag increases almost exponentially with speed, and you need to overcome the drag. At some point you'd have to double the power to achieve a meaningful improvement. Adding power is not the solution to going faster once you reach a certain point, and everything I've read and seen about the F-35 seems to indicate that it is pretty close to that point.
Not really; the frontal aspect of a F-35C is about the same as a F/A-18E/F Super Hornet:
https://www.f-16.net/forum/viewtopic.ph ... 2&p=248729
Comparing a F-35A to a Eurofighter or Rafale:
Also, the Super Hornet, Rafale, and Eurofighter all carry their weapons externally; external weapons, fuel tanks and pylons significantly increase drag. Not many fighters out there can claim that they can carry a pair of 2,000lb bombs, enough fuel for a typical strike mission and 2 air to air missiles, and fly at their top rated speed for as long as they have enough fuel to keep going. Every other fighter is subsonic only with anything hanging off of them.
Yes but the F18 has two engines, the F35 has the drag of a two engine aircraft but only has one
Aircraft that carry weapons, fuel etc on external pylons have a big advantage though, if they have to they can get rid of all that drag in an instant by jettisoning it and immediately improve their maneuverability and speed by a quantum leap
The F35 is always carrying that weight and drag with it even if it is internal
ThePointblank wrote:It's very telling that the Super Hornet requires 2 engines to push around an aircraft that weights almost the same as a single engined F-35C. And the F-35C can carry more weapons and fuel.
mxaxai wrote:ThePointblank wrote:It's very telling that the Super Hornet requires 2 engines to push around an aircraft that weights almost the same as a single engined F-35C. And the F-35C can carry more weapons and fuel.
So does the F-5. It's the total installed thrust, not the number of engines that matters. The F-18E has 196 kN, the F-35A has 191 kN (both with afterburners). And despite the draggy canted pylons, the F-18E can (theoretically) achieve M1.8.
ThePointblank wrote:mxaxai wrote:So does the F-5. It's the total installed thrust, not the number of engines that matters. The F-18E has 196 kN, the F-35A has 191 kN (both with afterburners). And despite the draggy canted pylons, the F-18E can (theoretically) achieve M1.8.
The F-18E can only reach its top speed clean, with no weapons or external fuel tanks. The F-35 will reach its top speed with a payload.
For example, an F-35C can only fly at Mach 1.3 in afterburner for 50 cumulative seconds, meaning that a pilot cannot clock 50 seconds at that speed, slow down for a couple seconds and then speed back up. However, the time requirements reset after the pilot operates at military power — an engine power setting that allows for less speed and thrust than afterburner — for a duration of three minutes.
The F-35B can fly for 80 cumulative seconds at Mach 1.2 or 40 seconds at Mach 1.3 without risking damage.
But for both the C and B models, flying at Mach 1.3 over the specified time limits poses the risk of inducing structural damage to the aircraft’s horizontal stabilizer.
SteelChair wrote:Didn't the SH versus Tomcat demonstrate that no parameter is more over-rated than top speed? Was the M2.44 top speed of the Tomcat ever tactically useful? What really counts are weapons, electronics, radar, networking, and reliability.
SteelChair wrote:Didn't the SH versus Tomcat demonstrate that no parameter is more over-rated than top speed? Was the M2.44 top speed of the Tomcat ever tactically useful? What really counts are weapons, electronics, radar, networking, and reliability.
Max Q wrote:A vital capability that hasn’t been mentioned is the most important.
A Navy pilot in an F18 that loses an engine hundreds of miles from the carrier or a land base can return for a safe landing on the other engine
An F35 pilot has no such option
Max Q wrote:A vital capability that hasn’t been mentioned is the most important.
A Navy pilot in an F18 that loses an engine hundreds of miles from the carrier or a land base can return for a safe landing on the other engine
An F35 pilot has no such option
meecrob wrote:The Navy and their F-8's and A-7's would like a word....